Added comment explaining the run loop business in CPScrollView.

Reviewed by me.

AppKit/CPScrollView.j

@@ -659,6 +659,7 @@ var CPScrollViewContentViewKey = "CPScrollViewContentView",
         _hasHorizontalScroller  = [aCoder decodeBoolForKey:CPScrollViewHasHScrollerKey];
         _autohidesScrollers     = [aCoder decodeBoolForKey:CPScrollViewAutohidesScrollerKey];
         
+        // Do to the anything goes nature of decoding, our subviews may not exist yet, so layout at the end of the run loop when we're sure everything is in a correct state.
         [[CPRunLoop currentRunLoop] performSelector:@selector(reflectScrolledClipView:) target:self argument:_contentView order:0 modes:[CPDefaultRunLoopMode]];
     }